wounds

Is That a Wombat on Your Belly, Or Are You Just Happy to See Me?

I attended a Ph.D. defense a few weeks ago on the effects of salmon lice (which are copepods, not insects) on their juvenile hosts. The student showed some gory photos and pointed out that for such a little fish, carrying a louse was like a human lugging around a raccoon on his back. Some mites can be just as burdensome, such as this Macrocheles muscaedomesticae (Scopoli) attached to the abdomen of an unfortunate Drosophila hydei Sturtevant.

Scanning electron micrograph of a Drosophila hydei carrying a female Macrocheles muscaedomesticae (image by HP)

Scanning electron micrograph of a Drosophila hydei carrying a female Macrocheles muscaedomesticae (image by HP)

Females of many species of Macrocheles (Mesostigmata: Macrochelidae) hitch rides on winged insects to move from a place to place, a phenomenon called phoresy. Strictly phoretic organisms do not feed on the host while attached. A great many mite taxa fall into this ‘purely phoretic’ category. Others may facultatively snack on the host while in transit. My colleague Lien Luong has investigated one such mite species, Macrocheles subbadius (Berlese), and its cactus-associated host Drosophila nigrospiracula Patterson & Wheeler. When Lien moved to the University of Alberta it proved difficult to replicate the system, in part because cacti are not common in this part of Alberta.  Compost bins are abundant, however, and Lien and her students are investigating the ecological relationship between two compost-associated species, Macrocheles muscaedomesticae and Drosophila hydei. Does M. muscaedomesticae feed on its host while attached, or is it just holding on? One way to test this is to determine whether the mite’s mouthparts pierce the fly’s integument. In this N = 1 sample, the mite just seems to be holding on firmly, probably uncomfortably so from the fly’s point of view.

mite biting medium close

Piercing or just pinching?

 

mite biting close

Looks like pinching, probably painfully.

But by definition, facultative parasites aren’t always parasitic. More mites must be examined, and other lines of evidence followed, such as presence of melanized wounds on hosts after the mites have dropped off, or presence of Drosophila DNA in the guts of the Macrocheles.

 

A(i)nt and gast(e)ropost

While at the Los Tuxtlas field station I had the opportunity to be attacked by numerous arthropods, including trombiculid mites (chiggers), numerous species of ants, and an urticating caterpillar. Don’t laugh about the caterpillar!  They can kill you. But the one that got me only left a caterpillar-shaped welt on my shoulder. I’ll describe two ant attacks of note. One involved an invasion of sleeping quarters by male and female ants after a hot day and heavy rainstorm induced a flight of reproductives. The bedroom walls and ceiling were covered in winged ants, which proceeded to fall down on the bed at night. One added both injury and insult by biting my bottom.

winged ant queen like the one that bit me in bed Los Tuxtlas 18 July 2014 sml

One of many reproductive female ants that swarmed the bedroom in Los Tuxtlas. Unfortunately, I don’t know the genus.

The next morning I took some photos of the remaining reproductives, which revealed that the males have grotesquely enlarged and protuberant ocelli.  A cursory Googling revealed that ocelli tend to be larger in reproductives of night-flying ant species, but I couldn’t find a good explanation for the sexual difference. This paper suggests that males of Myrmecia (a genus different from the that of the ants that fell on me) may have to engage in more intense visual tracking to find the females for mating.

ocelli of female vs male reproductive ants Los Tuxtlas 18 July 2014 sml

Heads of female (left) and male (right) reproductive ants showing the difference between the sexes in relative size and sphericality of the three ocelli.

The second ant attack occurred when I was peaceably watching a lecture on salticid taxonomy in the lab. Suddenly I felt a burning pain on my throat. Remnants of the crushed body of the perpetrator revealed that it was a Pseudomyrmex, probably P. salvini.  This ant was many times larger than the other species of Pseudomyrmex that had attacked my hand near Chamela, and it produced a goiter-like swelling commensurate with its size. I don’t know what induced it to stab me in the neck – sheer viciousness, perhaps. But on the bright side, the nasty nature of the Pseudomyrmex is probably why a particularly striking species of jumping spider mimics it. The a(i)nt pictured below with its model is a species of Synemosyna. They were common on the station walls and foliage.

Pseudomyrmex most likely salvini and Synemosyna mimic Los Tuxtlas 14 July 2014

Pseudomyrmex ant on left and a mimicking Synemosyna salticid on the right.

 So there is the gasteropost – on to the gastropost.  In Morelia we had much enjoyable food and drink, including a surprisingly good Mexican IPA, but there was also some awful stuff. One meal resulted in a three day trial of having my Edmontonian gut flora violently replaced with a Morelian community. After that had settled down, I decided I was digestively robust enough to sample a mysterious drink called a ‘Michelada’, which was advertised everywhere, but I had no idea what it might be. When the beverage arrived, this is what it turned out to be:

Michelada trimmed

Creating the Michelada – beer plus Clamato juice. Urgh. (photo by Wayne Maddison)

I managed to drink about a fifth of the concoction before the guts said ‘no’! Tastebuds concurred. But as odd as this beer+Clamato sounds, there is an equivalent in Alberta: the Red Eye. Why someone decided to replace the vodka in a Caesar with beer is unclear to me.

A more pleasant food experience took place in Mexico City after I had given my talk at UNAM. My host, Dr. Tila Pérez, took me and some other arachnologists to a traditional restaurant for lunch. There in addition to delicious moles (poblano, negro, verde and rojo), we sampled some unusual appetizers. My favourite was escamoles – fried ant juveniles (maybe a mixture of larvae and pupae) served with guacamole and eaten with tortillas. They tasted like buttery fried things, and I enjoyed them maliciously.

escamoles - fried ant pupae raised on agave roots Mexico City 28 July 2014

Fried baby ants – delicious revenge! (photo by Grislda Montiel)

Souvenirs

A few days ago we made it safely back to Canada after a month of collecting arachnids in Mexico.  While there we couldn’t resist picking up a few other souvenirs in addition to salticids and opilioacarids. One was a bottle of raicilla from the beautiful 400 year old town of San Sebastian del Oeste. Like tequila, raicilla is a distilled liquor made from agave, albeit from a different species in the same genus. The name may mean ‘little root’ but we’re guessing. Selling of raicilla has only recently been legalized according to this site.

raicilla and opilioacarids safe in Vancouver 6 March 2014

Raicilla and opilioacarids safe in Vancouver.

Therefore, I was legitimately able to bring in a bottle as a souvenir, along with my likewise legal container of opilioacarid mites (see permit above!). Unfortunately, the raicilla leaked a bit in my luggage, imbuing my trousers with a smoky flavour.

I also brought back some unintended mementos: clusters of itchy, supporating sores on my ankles resulting from bites of larval mites of the family Trombiculidae (Acari: Parasitengona). Trombiculids are known as chiggers in North America and scrub itch mites in Australia. As larvae, chiggers are parasites of vertebrates while as nymphs and adults they are free-living predators.  Despite common belief, chiggers do not burrow under your skin. Rather, those that bite humans usually attach only briefly and then drop off, leaving behind an itchy wad of spit that continues to cause irritation long after the wee mites are gone.

HPs right ankle with chigger bites 6 March 2014 compilation

My right ankle with chigger bites.

Losing blood in Mexico

We experienced many forms of personal exsanguination while in Mexico. Biting flies were diverse (Ceratopodinidae, Culicidae and even Simuliidae) though nowhere near as abundant as in Canada and only occasionally maddening. Ticks, on the other hand, were present in numbers that to me, as a resident of a province where human-biting ticks are relatively uncommon, were disconcerting. Tick-checks after fieldwork were a daily task, and Wayne and I competed for the honour of “most infested”.  On our second last field day at Rancho Primavera, I won with a whopping N = 42 ixodids.  We hope that none of the ticks we pulled from our integument were carrying noxious bacteria or viruses.

tick on beating sheet Rancho Primavera 3 March 2014

Tick on beating sheet.

tick embedded in Wayne Chamela field station 11 Feb 2014 A

Tick attached to Wayne.

But ticks and flies are lightweights in comparison to the champion bloodsuckers of Mexico – vampire bats.  We slept safely inside at night at so never got bitten; however, livestock aren’t so lucky. Bonnie Jáuregui, proprietor of Rancho Primavera, showed us fresh wounds on her horses that had been caused by feeding vampire bats (Desmodus rotundus).

vampire bat wound on horse Rancho Primavera 2 March 2014 sml

Vampire bat wound on horse’s neck.

She treated them by smearing a warfarin-containing cream on the wounds. When bats returned to feed on open wounds the next evening they would also ingest some warfarin. Then, because vampire bats frequently share their blood meals with roost-mates via regurgitation, the anti-clotting agent would not only affect the bat that fed on the wound directly but also its friends and relatives.

warfarin cream to kill vampire bats Rancho Primavera 2 March 2014 sml B

Warfarin, yes, garlic and wooden stakes, no.